Technical Field
Embodiments consistent with the presently-claimed invention are related to laser projection systems and, in particular, to methods and systems for creating an area of denied visual access. Embodiments are further related to characterizing sensors detected by reflection and retroreflection of the projected laser pattern.
Discussion of Related Art
Non-lethal directed energy systems are increasingly used by law enforcement because of their ability to reduce fatalities and collateral damage. Some directed weapon systems use electromagnetic energy, such as lasers, to visually impair identified visual systems temporarily or to warn of suspected threats prior to using other protective measures. Other directed energy systems may be used proactively to protect a person or an object from unknown targets that may be in the surrounding area. For example, local authorities may wish to secure an area in preparation for a public appearance by a government official or a moving vehicle.
In certain situations, however, existing directed energy systems utilizing lasers may be of limited effectiveness. For example, existing system may be ineffective when applied to large geographic areas. Existing systems have to blanket a large area with a more or less uniform illumination or scan the area with a single spot or line. The first case requires a very high power source; while the second approach is limited by the time required to scan a large area with a single spot or line. The scan time may limit dwell time and may require impractical rates of motion for large areas or multiple systems. In another example, some existing systems are designed to cause temporary vision impairment over a narrow range within a target area at some distance from the object or person to be protected. Often, these systems are aimed by an operator at a single location or manually swept across a target area. As a result, the ability to neutralize an undisclosed threat in a broad area is limited by the operator. Further, sufficient dwell time may not be available to cause the desired effects of aversion or disruption. Some existing systems have difficulty denying visual access across target areas having varying geographic and structural conditions. Some systems, for example, may be safely operated when targets are at an extended distance or widely dispersed. These systems, however, may create eye safety concerns when used at closer distances, such as in narrow corridors or within a building.